1. Field of the Invention
The present invention relates to a semiconductor laser and a manufacturing method of the same, and more particularly to a semiconductor laser suitable for the emission of visible light and a manufacturing method of the same.
2. Related Background Art
Several years ago, a He-Ne gas laser was used in most cases to generate a bright red laser beam. Recently, the practical use of a visible light semiconductor laser which uses GaInP as an active layer has been so advanced that a light having a wavelength of 0.67 .mu.m is generated by the semiconductor laser.
However, since the wavelength of 0.67 .mu.m is longer than the wavelength of 0.6328 .mu.m of the He-Ne gas laser, the visual sensitivity thereto is lower than that of the He-Ne gas laser. As a result, in the field of the semiconductor laser, there is a demand for further shortening the wavelength to approach to the wavelength of 0.6328 .mu.m of the He-Ne gas laser. On the other hand, it has been proved that the emission wavelength can be further shortened by adding Al to the active layer. However, when Al is added to the active layer, non-radiative recombination centers associated with Al increase and the confinement of carriers is diminished by the large band gap of the active layer. As a result, the laser oscillation is hard to be obtained and it is difficult to continuously oscillate at room temperature, or the durability is short even if the continuous oscillation is attained.